CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Net sales	$ 548,184	$ 491,611
Cost of sales	438,414	389,262
Gross profit	109,770	102,349
Selling, general and administrative expenses	79,937	84,655
Restructuring charges	222	308
Income from operations	29,611	17,386
Interest expense	(5,317)	(6,802)
Interest income and other expense, net	(678)	(941)
Earnings before provision for income taxes	23,616	9,643
Provision for income taxes	2,907	21,540
Net earnings (loss) available to common shareholders	20,709	(11,897)
Class A Common Stock [Member]
Net earnings (loss) available to common shareholders	$ 3,521	$ (2,113)
Net earnings (loss) per common share:
Common shares - basic and diluted (in dollars per share)	$ 1.62	$ (0.97)
Weighted-average shares outstanding:
Common shares - basic and diluted (in shares)	2,175	2,175
Dividends paid per common share:
Common shares (in dollars per share)	$ 0.24	$ 0.24
Class B Common Stock [Member]
Net earnings (loss) available to common shareholders	$ 17,188	$ (9,784)
Net earnings (loss) per common share:
Common shares - basic and diluted (in dollars per share)	$ 1.73	$ (0.99)
Weighted-average shares outstanding:
Common shares - basic and diluted (in shares)	9,939	9,857
Dividends paid per common share:
Common shares (in dollars per share)	$ 0.28	$ 0.28